... the engagement in R&D, manufacturing and international trade of precision steel tubes, and has more than 3500 tons’ manufacturing capability. ... surface roughness Ra0.4-0.6. The types of steel tubes include 10#, 20#, 35#, 45#, 160Mn, 20GrMo, 35GrMo, 40Gr. ... anchoring machinery and construction machinery. JYDR supplies precision tubes and a lot of spare parts for global incorporations.JYDR passed the ...